General Description: Delicate annual herb with fibrous roots. This 2-4in (5-10cm) tall plant has submerged and floating greenish-purple leaves. Submerged leaves are thin and narrow, 0.4in (1.0cm) in length, and arranged in a basal rosette. Paired floating leaves, 0.32in (0.8cm) in length, are ovate, rounded, and surround a single white flower, all attached to a thin stem. Flowers are borne in the axils of both types of leaves. Only the floating flowers are opened. Amphianthus flowers from March through April. It has been speculated this plant produces seeds asexually which may threaten its ability to adapt. The plant's life cycle is usually only three or four weeks. The fruit is a capsule 0.12in (2-3mm) wide and 0.04in (1mm) containing many banana-shaped, dark brown seeds, 0.04in (1mm) long. Fruiting is from April to May.
General Habitat: Granite outcrops occur on large isolated domes or gently rolling flatrocks in full sunlight. This plant typically occurs in shallow flat-bottomed pools found on the crest and flattened slopes of unquarried outcrops. These pools range in size from 0.3-10.0 yd2 (0.3-10.0 m2), the vast majority ranging from 0.5-1.0 yd2 (0.5-1.0 m2). These pools retain water for several weeks following a heavy rain and completely dry out with summer droughts. The seeds can lie dormant over several seasons until moisture becomes available.
